1. Field of the Invention
The present invention relates to a worm pump for delivering a metal melt, which comprises a mounting flange and a tubular pump housing mounted on, and suspended from, the mounting flange. The pump housing defines a lower inlet for receiving the metal melt and an upper outlet for delivering the metal melt. A drive motor is mounted on the mounting flange, the drive motor having a pump shaft extending into the tubular pump housing and comprising a conveyor screw between the inlet and outlet. A guide means is provided for the pump shaft at a lower end thereof.
2. Description of the Prior Art
The possibility of a dependably operating melt delivery, which can be metered, from a container, such as a melt furnace, to a casting machine is a pre-condition for the proper feeding of the melt to the casting machine. In feeding metal melts to a casting machine, a flow of usually less than 100 liters/minute is involved, and the melt delivery is either continuous or intermittent. The delivery systems for delivering metal melts are subjected to considerable stresses, due to the high melt temperatures, danger of clogging when the melt solidifies, the frequent corrosiveness of the melt material, the occurrence of shrinking forces, and the temperature-dependent changes in the shape of the melt. Up to now, no really satisfactory pumps have been available for such a delivery system. The known worm or screw pumps that have been used have rigid pump shafts mounted in fixed rotary bearings. They cannot successfully handle the difficulties due to expansion of the material and they are subject to failure because of freezing of the metal melt. Rotary pumps for emptying galvanizing furnaces can be used only for a short time and for relatively large quantities per time unit. Inductive and conductive piston pumps are complicated and cannot be used for a continuous delivery. Mechanical ladles with their batch-wise delivery and large space requirements do not satisfy the operating conditions of modern casting operations.